In the prior art, climbing formworks are used to erect a concrete structure, for example a skyscraper, in a number of successive casting steps. Such climbing formworks may be relocated between casting steps or can move upwards on their own. The latter type is usually referred to as a self-climbing formwork. Examples are shown in US 2010/0038518 A1 or WO 2013/110126 A1. Another type of climber formwork is disclosed in WO 2011/127970.
EP 1 806 559 discloses a surveying procedure for a high-rise building subject to tilt effects and hampered use of ground-level reference points. The system uses at least three receivers of a satellite-based positioning system in order to determine the positions of three reference points, equipped with reflectors, on the uppermost level of the building under construction. The reference points that have been ascertained via the receivers are localized with an electro-optical geodesic instrument associated with the structure. In this way the position of the instrument relative to the three reference points can be acquired, and the instrument is referenced to the absolute coordinate system of the satellite-based positioning system. Furthermore, a tilt of the structure is determined gravimetrically, with a tilt sensor positioned on the uppermost construction level. Further gravimetric tilt sensors may be provided on different construction levels. The measurements are used for matching the geodesic instrument to a coordinate system that dynamically depends on the tilt of the building. However, the prior art of EP 1 806 559 is restricted to the determination of a central axis of the building during erection. This would be insufficient to identify the correct position of the formwork.
In the prior art, it is further known to compare discrete measurements of the previous casting segment as built with the construction plan of the building for the purpose of deriving correction values for the next casting segment. For example, at least two reference positions of each wall of the previous casting segment may be measured. In the next step, a geodesist calculates a multitude of correction values for the coming casting segment based on the deviations of the previous casting segment from the intended arrangement. In the preparation of the casting step, the formwork is adjusted such that the correction values are accounted for in the formation of the uppermost casting segment.
In the prior art, it was necessary for the operators of the climbing formwork to control the position of the upper end of the formwork, as it may not be possible to accurately arrange the lower end of the formwork in a defined casting position. For adjusting the upper end of the formwork, a laser plumb tool may be arranged on the working platform of the climbing formwork. The operator may then check the horizontal distance between the laser radiation from the laser plumb tool and the upper edge of the formwork. However, this adjustment is cumbersome, time-consuming and prone to errors.
Thus, there is a need for enhanced surveying and adjustment procedures during erection of concrete structures in view of minimizing efforts for manual measurements.
On the other hand, JP 2000314235 A discloses a method and a device for controlling a slip form capable of rapid measurement and operation. A plurality of reference points are provided on a slip form to form a placement space of the designed shape while sliding a concrete to be placed, and a target plate is fixed to each reference point. When the reference point is at the specified horizontal position in the designed shape, a perpendicular laser beam is emitted from the ground to pass the reference point on the target plate. The displacement vector from the reference point to the intersection of the target plate with the perpendicular laser beam is detected by a camera fixed to the slip form. The measured shape of the slip form and the difference between the measured shape and the designed shape are calculated based on the displacement vector at a plurality of reference points. An operation output to minimize the difference is calculated, and the slip form is operated by a hydraulic jack according to the operation output.
This prior art attempts to adjust the position of the formwork with respect to laser plummets arranged on the ground. This method entails a number of drawbacks. First, the laser plummet has a maximum reach that possibly is not sufficient for high-rise buildings. Second, the path of the laser emitted from the plummet could be affected by temperature differences or movements of the building across the levels of the concrete structure. Third, the target plates need to be in the field of view of the laser plummet on the ground. This may be impossible to realize with state of the art formworks. Also, concrete structures whose layout varies with height will preclude the possibility of arranging the laser plummet on the ground and determine an absolute formwork position.
It is therefore an object of the invention to alleviate some or all of the drawbacks of the prior art and to propose a climbing formwork and a method for erection of a concrete structure that facilitates adjustment of the formwork before casting.
This object is met by providing a climbing formwork for erection of a concrete structure by successively casting a plurality of casting segments, and a method for erecting the concrete structure by successively casting a plurality of casting segments.
Thus, the climbing formwork of the instant invention comprises
at least a first form element with an outer surface for delimiting a cavity to receive concrete for forming an uppermost casting segment, the first form element having an upper end and a lower end,
a first support structure to support the first form element,
a first tilt sensor for measuring a tilt of the first form element,
a first measuring unit for measuring a horizontal distance between the outer surface at the lower end of the first form element and an outer surface at an upper end of a previous casting segment, the outer surface at the upper end of the previous casting segment facing the outer surface of the first form element.
a processing unit communicating with the first tilt sensor and the first measuring unit, the processing unit being arranged for calculating a target tilt of the first form element using the measurement of the horizontal distance between the lower end of the outer surface of the first form element and the upper end of the outer surface of the previous casting segment, the processing unit further being arranged for determining a deviation between an actual tilt and the target tilt of the first form element.
For bringing the first form element into a casting position, the first form element is tiltable and movable at least in a horizontal direction. The first form element is mounted on a first support structure, which preferably comprises a working platform. In the invention, the first tilt sensor is adapted for measuring the tilt, i.e. the inclination with respect to a vertical plane, of the first form element. In the preparation of the present casting step, the first form element may be moved into a casting position, in which the lower end of the first form element is brought into contact with the upper end of the casting segment of the previous casting step. However, due to obstacles in the pathway of the first form element or due to other reasons it may not be possible to press the lower end of the first form element against the previous casting segment such that a gap may be formed between sections of the lower end of the first form element and sections of the upper end of the previous casting segment. Such gap may have a width (i.e. a horizontal extension) of several millimeters or may even range to one centimeter. For larger gaps the casting would be impossible due to concrete leaking from the cavity. It may not be possible to clear the obstacle in the pathway of the first form element. In this case, the casting segment has to be formed while the lower end of the first form element is at least partially out of contact with the upper end of the previous casting segment. The processing unit is arranged for determining the gap between the lower end of the first form element and the upper end of the previous casting segment taking into account the measurement provided by the first measuring unit. In the next step, the processing unit calculates a target tilt of the first form element such that the upper end of the first form element is in a target horizontal position. Preferably, the target horizontal position of the upper end of the first form element is predetermined by a surveyor, in particular a geodesist, for the casting segment to be in conformity with a building plan. Thus, the relative position of the lower end of the first form element and the upper end of the previous casting segment is used as an input to the calculation of the target tilt of the first form element in preparation of the next casting step. Thus, the climbing formwork of the instant invention monitors the horizontal position of the lower end of the first form element with respect to the upper end of the previous casting segment (i.e. the casting segment of the level of the concrete structure directly below the uppermost casting segment) for adapting the tilt of the first form element accordingly.
While JP 2000314235 A adjusts a formwork with respect to measuring devices on the ground, the invention provides for an iterative approach, in which the first form element is adjusted with respect to the casting segment below the cavity for casting the uppermost casting segment.
In this way, the accuracy of the positioning of the first form element in the casting position may be significantly improved. It is made easier to compensate for deviations of the previous casting segment from the construction plan. By measuring both the tilt and the horizontal distance between the lower end of the first form element and the previous casting segment, the workers involved in the erection of the building may be liberated from the laborious and dangerous task of manually controlling the horizontal position of the upper end of the first form element when positioning the first form element in the casting position.
This procedure may be repeated several times for erecting a plurality of casting segments giving rise to a multilevel concrete structure. It is an advantage of the invention that the positioning of the first form element is done relative to the casting segment of the previous casting step.
Preferably, the first measuring unit is arranged at the lower end of the first form element, wherein preferably at least two first measuring units are arranged in a distance from one another in a horizontal direction transverse to a translational displacement of the first form element into a casting position. In this way, a gap formed between the first form element and the previous casting segment may be easily and reliably detected such that the tilt of the first form element may be adjusted accordingly.
In a preferred embodiment, the first measuring unit comprises a wave transmitting and receiving device. This embodiment yields accurate results, dispenses with movable parts and avoids wear even under intense use.
In a first preferred variant, the wave transmitting and receiving device is a laser distance sensor, preferably based on laser triangulation. The laser distance sensor may comprise a laser, optionally a transmitter lens, optionally a receiver lens and a light receiving element.
In a second preferred variant, the first measuring unit comprises an ultrasonic wave transmitting and receiving device. The ultrasonic wave transmitting and receiving device may comprise an ultrasonic element for emitting an ultrasonic wave and receiving a reflection of the ultrasonic wave.
In a particularly simple alternative, the first measuring unit comprises a contact element, preferably a pin, moveable relative to the first form element from a first position into a second position when the first form element is moved into a casting position. In the first position, the contact element extends beyond the plane of the outer surface of the first form element. Preferably, the first measuring unit comprises a spring element which biases the contact element in direction of the first position. For example, the contact element may comprise a pin which is moved from the first (rest) position into the second (withdrawn) position when pressed against the upper end of the previous casting segment. Preferably, the first measuring unit further comprises an encoder, particularly a magnetic or optical encoder, for measuring a position of the contact element, which can be communicated to the processing unit. In a preferred variant, the encoder detects a linear shift, preferably in a substantially horizontal direction, of the contact element when the first form element is brought in abutment with the outer surface of the previous casting segment. When arranging the first form element in the casting position, the contact element is moved from the first (rest) position into the second (fully withdrawn) position, if the horizontal distance between the lower end of the first form element and the upper end of the previous casting segment is substantially zero. However, if there is a gap between the lower end of the first form element and the upper end of the previous casting segment due to obstacles in the path of the first form element the contact element is moved to a partially withdrawn position between the first position and the second position. Thus, the movement of the contact element when the first form element approaches the casting position is indicative of the formation of a gap between the lower end of the first form element and the upper end of the previous casting segment. The data from the first measurement unit is then communicated to the processing unit for calculating a target tilt of the first form element.
In a preferred embodiment, the first measuring unit comprises a sensor housing having a front surface facing the cavity, the front surface being set back against the outer surface of the first form element. Thus, the front surface of the housing of the first measuring unit is spaced from the outer surface of the first form element in horizontal direction away from the cavity for receiving concrete. In this way, the first measuring unit does not interfere with bringing the first form element in abutment with the upper end of the previous casting segment.
In a preferred embodiment, the first measuring unit, preferably also the processing unit, are mounted on the first form element, while the first support structure is free from components of the first measuring device. This arrangement is particularly simple. Also, the first form element may be delivered to the construction site fully equipped with the measuring device.
In another preferred embodiment, the first measuring unit for measuring a horizontal distance between the lower end of the outer surface of the first form element and the upper end of the outer surface of the previous casting segment is arranged for measuring a horizontal displacement of the lower end of the first form element with respect to the first support structure.
Thus, the first measuring unit of this embodiment is provided for determining the horizontal displacement of the lower end of the first form element with respect to a stationary reference point of the first support structure (i.e. with a reference point not movable with the first form element). The first measuring unit may also be arranged for determining a vertical displacement of the first form element with respect to the stationary reference point of the first support structure. Preferably, the stationary reference point is located at the working platform of the first support structure. In this embodiment, the processing unit is arranged for determining the gap between the lower end of the first form element and the upper end of the previous casting segment taking into account the measurement of the horizontal displacement of the lower end of the first form element with respect to the first support structure. For the purpose of calculating the displacement of the first form element, the processing unit may use additional information stored in a data storage unit connected to the processing unit. Such additional information may relate to the arrangement of the first support structure with respect to the previous casting segment and/or to the dimensions of the first form element. In the next step, the processing unit calculates a target tilt of the first form element such that the upper end of the first form element is in a target horizontal position. Preferably, the target horizontal position of the upper end of the first form element is predetermined by a surveyor, in particular a geodesist, for the casting segment to be in conformity with a building plan. Thus, the relative position of the lower end of the first form element and the upper end of the previous casting segment is used as an input to the calculation of the target tilt of the first form element in preparation of the next casting step. Thus, the climbing formwork of the instant invention monitors the horizontal position of the lower end of the first form element with respect to the upper end of the previous casting segment for adapting the tilt of the first form element accordingly. In this way, the accuracy of the positioning of the first form element in the casting position may be significantly improved. It is made easier to compensate for deviations of the previous casting segment from the construction plan. By measuring both the tilt and the horizontal displacement of the lower end of the first form element, the workers involved in the erection of the building may be liberated from the laborious and dangerous task of manually controlling the horizontal position of the upper end of the first form element when positioning the first form element in the casting position.
For the purposes of the present disclosure, the positional and directional indications, like “lower”, “upper”, “horizontal” and “vertical”, refer to the arrangement of the climbing formwork in use when erecting the building.
In a particularly preferred embodiment, the first measuring unit comprises a first reference element arranged on the first support structure and a second reference element arranged on the first form element. When the first form element is moved to the casting position, the second reference element fixed to the first form element is moved relative to the first reference element fixed to the first support structure. The first measuring unit is arranged for measuring the horizontal distance between the first and second reference element, which is indicative of the position of the lower end of the first form element relative to the upper end of the previous casting segment. Thus, the processing unit receiving the measurements from the first measuring unit may determine the width of the gap between the lower end of the first form element and the upper end of the casting segment of the previous casting step. The tilt of the first form element may then be adjusted accordingly.
For obtaining reliable, accurate positional information about the lower end of the first form element relative to the previous casting segment, the first measuring unit preferably comprises an optical device, in particular a camera, the optical device being arranged for locating the first reference element on the first support structure and the second reference on the first form element, respectively. The first and second reference element is located in the field of view of the optical device, respectively. The processing unit is arranged for calculating a horizontal distance between the first and second reference element from the data provided by the optical device. In a particularly preferable embodiment, the optical device is a camera arranged for obtaining a picture including the first and second reference element. In this case, the processing unit may include an image processing unit, as is per se known in the art, to derive the horizontal distance between the first and second reference element from the picture taken by the camera.
In a preferred embodiment, the first and second reference element comprises a first and second barcode element, respectively. The optical device may be used to determine the center points of the first and second barcode element. The first and second barcode element may also have a unique first and second identification code. The measuring unit and the processing unit may be arranged for reading out the first and second identification code. Preferably, two-dimensional matrix barcode elements are used, known as QR (Quick Response) Codes.
For facilitating the measurement of the horizontal displacement of the lower end of the first form element, the second reference element is preferably arranged at the lower end of the first form element.
In a preferred embodiment, the optical device and/or the tilt sensor are arranged on the first form element.
In a preferred embodiment, the processing unit is arranged for comparing the horizontal displacement of the second reference element with respect to the first reference element with a horizontal distance between an outer surface of a previous casting segment and the first reference element, the processing unit further being arranged for calculating a gap between the first form element and the outer surface of the previous casting segment. Due to obstacles in the path of the first form element between a withdrawn position and a casting position, a gap may extend between facing outer surfaces of the first form element and the previous casting segment. By measuring the horizontal displacement of the lower end of the first form element the gap may be measured and accounted for in the calculation of the target tilt of the first form element.
In a further preferred embodiment, a third reference element is arranged on the first support structure, the third reference element being arranged in a distance from the first reference element in a direction away from the cavity, the optical device being arranged for locating the third reference element. In this embodiment, the first form element may be easily arranged in a defined withdrawn position, which facilitates the positioning of reinforcements before the first form element is moved into the casting position.
In a particularly preferred embodiment, the processing unit is arranged for calculating a deviation between the actual horizontal position of the first form element and a target withdrawn position of the first form element using the location of the third reference element. Thus, the third reference element is arranged further away from the cavity in comparison to the first reference element. By monitoring the horizontal distance between the third reference element fixed at the first support structure element and the second reference element movable with the first form element, preferably by means of the optical device mentioned above, the first form element may be easily arranged in a defined withdrawn position, which is spaced apart from the casting position. This withdrawn position may be used for arranging the reinforcements in the cavity before the first form element is brought into the casting position, in which the first form element delimits the cavity for receiving concrete. The deviation of the first form element from the withdrawn position may be shown on the display device, signaled by the signal device and/or used as an input for the drive unit connected to the processing unit, respectively.
In a preferred embodiment, in the withdrawn position of the first form element a distance piece for a reinforcement of the casting segment to be cast projects from the first form element. In this way, the reinforcement may be easily arranged in the space intended to receive concrete in the casting step, while the first form element is in the withdrawn position. Due to the distance piece, the reinforcements may be prevented from extending beyond their intended position. Preferably, the withdrawn position is spaced from the casting position such that the reinforcements are in contact with the distance holder when the first form element is in its withdrawn position. After the positioning of the reinforcements is completed, the distance holder may be removed such that the first form element may be safely moved into the casting position, without danger of a collision with the reinforcements previously arranged. Thus, any damages of the first form element and its first support structure may be prevented.
Preferably, the distance piece is mounted on the first form element. In the withdrawn position, the distance piece preferably extends essentially perpendicularly to the main plane of the first form element. In a preferred embodiment, the distance piece is pivotably connected to the first form element, preferably at the upper end thereof. In this case, the distance piece may be pivotable between a stowed position for the casting position of the first form element and an operating position for the withdrawn position of the first form element. In the operating position, the distance piece projects from the first form element in direction of the space for arranging the reinforcements. In an alternative embodiment, the distance piece may be detachably connected to the first form element.
In a preferred embodiment, the tilt sensor comprises a laser plummet (plumb laser) device, preferably comprising a laser radiation source for emitting a vertical laser beam, a preferably self-leveling support for mounting the laser radiation source thereon, a target plate for receiving the vertical laser beam from the laser radiation source and a camera unit for detecting a displacement of an intersection of the vertical laser beam with the target plate. Preferably, the laser radiation source is mounted on one of the lower or the upper end of the first form element, whereas the target plate, preferably also the camera unit, is mounted on the other of the lower and the upper end of the first form element. This embodiment allows for easy adaptation to different heights of the first form element. Furthermore, the installation and transport of the first form element is facilitated. Also, the laser plummet device may be easily replaced. For achieving accurate and reliable results, it is preferred if the self-leveling support is connected to a dampening device for dampening vibrations of the self-leveling support.
In another preferred embodiment, the tilt sensor comprises a longitudinal element, preferably a measuring rod or a wire or string, mounted on the first form element, the longitudinal element preferably extending from an upper end of the first form element to the lower end of the first form element, the longitudinal element preferably being connected to the first form element at the upper end and at the lower end of the first form element, respectively. This embodiment is particularly advantageous in that the accuracy of the measurement of the inclination of the first form element is significantly increased. In many cases, the shape of the first form element may only be provided with limited precision. In such cases, measuring the tilt of the first form element at an arbitrary position along the length of the first form element would not yield reliable results. In the embodiment mentioned before, this problem may be avoided by connecting the longitudinal element to the first form element at two positions spaced apart from one another, preferably at the upper and the lower end of the first form element. In this case, deformations of the first form element are less detrimental to the tilt measurements.
If the longitudinal element is a wire or string, it is preferred that the wire or string is connected to a tensioning device. This variant is particularly light-weight and reliable. The wire or string may be housed in a hollow element, in particular in a pipe. In this way, the risk of damages to the wire or string is significantly reduced.
If the longitudinal element is a measuring rod, the installation is particularly simple and costs may be reduced.
In this embodiment, it is preferable if the longitudinal element is connected to the first form element via a first pivoting support preferably at the lower end of the first form element and a second pivoting support preferably at the upper end of the first form element. Thus, in this embodiment the longitudinal element is supported, preferably on opposite ends, by a first pivoting or tilting support and a second pivoting or tilting support. In this way, the arrangement of the longitudinal element accurately reflects the inclination of the first form element.
In a particularly preferred embodiment, the processing unit is connected to a data storage unit storing a correction value for a position of the first form element, the correction value being derived from a deviation between a position of a previous casting segment from a reference position of the previous casting segment, the processing unit being arranged for calculating the target tilt of the first form element using the correction value for the position of the first form element in addition to the horizontal distance between the lower end of the outer surface of the first form element and the upper end of the outer surface of the previous casting segment. As is known from the prior art, a multitude of correction values may be derived for individual sections of the casting segment to be casted. Each correction value reflects a deviation of a certain measuring point of the position of the previous casting segment as built, in particular at an upper end thereof, from its reference position, i.e. its intended position as shown in the construction plan. A number of techniques are known for obtaining measuring points of the previous casting segment as built for calculating the correction values therefrom. For example, laser plumb tools may be used. For this reason, detailed explanations thereof may be omitted in this disclosure. However, according to the instant invention the formation of the casting segment is improved by using not only the correction values but also the input from the first measuring unit. In this way, the target tilt of the first form element may be accurately calculated without a need for manually measuring the horizontal position of the upper end of the first form element.
The positioning of the first form element may be improved in several ways based on the determination of the deviation between the actual tilt and the target tilt of the first form element.
In a preferred embodiment, the processing unit is connected to a displaying device for displaying the deviation between the target tilt and the actual tilt of the first form element. In this particularly simple embodiment, the displaying device displays information about the deviation of the first form element from its target position. This information can be used to manually change the inclination of the first form element.
In a further preferred embodiment, the processing unit is connected to a signaling device for signaling the deviation between the target tilt and the actual tilt of the first form element. The signaling device may be arranged for outputting an acoustic or a visual signal.
In a further preferred embodiment, the climbing formwork comprises a drive unit for adjusting the first form element relative to the first support structure, the drive unit preferably comprising a first tilting unit for tilting the first form element and/or a first horizontal displacement unit for horizontally displacing the first form element and/or a first vertical displacement unit for vertically displacing the first form element.
In a further preferred embodiment, the processing unit is connected to the first tilting unit for tilting the first form element in accordance with the target tilt. In this embodiment, the first form element may be adjusted by means of the first tilting unit, in particular by pivoting the first form element about a horizontal pivot axis.
According to the instant invention, the method for erecting a concrete structure by successively casting a plurality of concrete segments comprises the steps of
arranging a climbing formwork having at least a first form element in a casting position, wherein the first form element delimits a cavity to receive concrete for forming an uppermost casting segment,
supporting the first form element in the casting position,
measuring an actual tilt of the first form element,
measuring a horizontal distance between the lower end of the outer surface of the first form element and the upper end of the outer surface of the previous casting segment,
calculating a target tilt of the first form element using the measurement of the horizontal distance between the lower end of the outer surface of the first form element and the upper end of the outer surface of the previous casting segment,
determining a deviation between the actual tilt and the target tilt of the first form element.
In a preferred embodiment, the method further comprises the steps of
storing a correction value for a position of the first form element, the correction value being derived from a deviation between a position of a previous casting segment from a reference position of the previous casting segment,
calculating the target tilt of the first form element using the correction value for the position of the first form element and the horizontal distance between the lower end of the outer surface of the first form element and the upper end of the outer surface of the previous casting segment.
In a preferred embodiment, the method further comprises at least one of
displaying the deviation between the target tilt and the actual tilt of the first form element,
signaling the deviation between the target tilt and the actual tilt of the first form element,
tilting the first form element in accordance with the target tilt by means of a drive unit.